1. Field of the Invention
The present invention relates to an image display apparatus for reproducing digital data representing an image and recorded on a recording medium, such as a digital video disk (DVD) or a video compact disk (VCD), and a special picture reproduction controller for controlling the image display apparatus.
2. Description of the Prior Art
When recording digital picture data obtained by converting image signals on a recording medium, such as a DVD or a VCD, the digital picture data is compressed. A MPEG (motion picture coding experts group) system, which is one of picture data compressing systems, has been examined for practical application.
A special image reproducing method proposed in, for example, JP-A No. 9-46712 to achieve special picture reproduction, such as reverse picture reproduction, of picture data recorded on a DVD uses only a frame memory necessary for ordinary forward picture reproduction. In reverse picture reproduction by this previously proposed special image reproducing method, picture data representing a group of pictures including at least one frame of an intraframe predictive coded picture (I-picture), a plurality of frames of interframe forward predictive coded picture (P-picture) and interframe bidirectional predictive coded picture (B-picture)is decoded and displayed in an order reverse to that in which the picture data is recorded on a DVD.
In reproducing picture data having a field structure in which one frame consists of two fields by such a method, the values of temporal reference (TR) information written to the picture headers of two picture data are detected, the two picture data are regarded as a pair of picture data if the two values of TR information are equal to each other, and the two picture data are combined to reproduce a picture for one frame.
Since a conventional image display apparatus and a conventional special picture reproduction controller are constituted so as to carry out the foregoing image reproducing method, picture data having a pair of fields are combined to reproduce a picture for one frame in a forward reproduction mode. Therefore, in a reverse reproduction mode, the first field and the second field of a first frame are reproduced in that order, and then the first field and the second field of a second frame which is to be reproduced before the first frame in the forward reproduction mode are reproduced in that order. If picture data is reproduced by this method in the reverse reproduction mode, a picture element which moves from the left side toward the right side on a screen when the picture data is reproduced in the forward reproduction mode moves a long distance toward the left in the first field of a frame, and then moves toward the left from a middle of the moving distance in the second field of the frame, so that the picture element moves in a zigzag way and pictures thus reproduced in the reverse reproduction mode look unnatural.
Accordingly, it is an object of the present invention to provide an image display apparatus capable of displaying pictures in natural reverse motions when reproducing picture data in a special picture reproduction mode, such as a reverse reproduction mode, a reverse slow-motion reproduction mode or a reverse high-speed reproduction mode, and a special picture reproduction controller for controlling the image display apparatus.
With the foregoing object in view, according to a first aspect of the present invention, an image display apparatus comprises a read bank specifying means for sequentially specifying banks of a memory from which picture data is read so that fields to be reproduced are reproduced in order reverse to that in which the same are read in a forward reproduction mode. When the picture data is thus reproduced in the special picture reproduction mode, such as the reverse reproduction mode, the reverse slow-motion reproduction mode or the reverse high-speed reproduction mode, pictures can be reproduced in natural reverse motions.
According to a second aspect of the present invention, an image display apparatus may further comprise a scanning line reversing means for reversing the order of scanning lines in the first field and the second field of a frame for the forward reproduction mode when reproducing pictures of frames each consisting of two fields in the reverse reproduction mode. The effect of the image display apparatus in the second aspect of the present invention is similar to that of the image display apparatus in the first aspect of the present invention.
According to a third aspect of the present invention, a special picture reproduction controller comprises a read bank specifying means for sequentially specifying banks of a memory from which picture data is read so that fields are reproduced in order reverse to that in which the fields are reproduced in a forward reproduction mode when reproducing the fields in a reverse reproduction mode. The effect of the special picture reproduction controller in the third aspect of the present invention is similar to that of the image display apparatus in the first aspect of the present invention.
According to a fourth aspect of the present invention, the special picture reproduction controller may further comprise a scanning line reversing means for reversing the order of scanning lines in the first field and the second field of a frame for the forward reproduction mode when reproducing pictures of frames each consisting of two fields in the reverse reproduction mode. The effect of the image display apparatus in the second aspect of the present invention is similar to that of the image display apparatus in the first aspect of the present invention.